Sizes Of Shells Research Articles

Principal component analysis (PCA) of bioactive compounds and antioxidant activity of various sample particle sizes of sea urchin shells from coastal area of Lombok Island

The most common technique in increasing pharmacological activity is by reducing sample particle size. This study aims to investigate the impact of different particle sizes on the bioactive composition and antioxidant activity of sea urchin shells collected from the coastal areas of Lombok Island. Sea urchin shell powders ranging in particle sizes <45 µm, >45 µm, <125 µm, >250 µm, and >2000 µm were extracted using 70% ethanol via the cold maceration method. The composition of bioactive compounds was analyzed using GC-MS, while antioxidant activity was evaluated using the DPPH free radical scavenging assay. Principal Component Analysis (PCA), conducted using Minitab software, was employed to summarize the interrelationships among all variables in the study. The findings reveal that each particle size exhibits a distinct composition of bioactive compounds. The highest concentrations of bioactive compounds and the greatest antioxidant activity were observed in samples with particle sizes >45 µm. PCA identified several bioactive compounds, such as lanolin, palmitic acid, myristic acid, stearic acid, heptadecene-(8)-carboxylic acid, 5,8,11,14-eicosatetraenoic acid, and 9-hexadecanoic acid, contributing significantly to this antioxidant effect. Reducing the particle size was found to alter the composition of bioactive compounds and enhance antioxidant activity. These bioactive compounds show promise for further exploration in the development of new drugs derived from marine sources.

Morphological variation in first-formed shells of the Ordovician Paucicrura–Diceromyonia brachiopod lineage of North America

Abstract First-formed shells of several species of Dalmanellidae (Brachiopoda) from the Ordovician (Katian) of North America were measured and compared: Cincinnetina multisecta, Diceromyonia tersa, Diceromyonia storeya, Paucicrura corpulenta, Paucicrura rogata, and Paucicrura sillimani. Sizes and structures of the first-formed shells suggest that members of this family had planktotrophic subadults, with some species showing indications of only an unshelled larval stage and others showing both a larval stage and a shelled juvenile stage. This differs from modern rhynchonelliformean brachiopods, which all possess only a lecithotrophic larval stage. The range of sizes of first-formed shells of most studied species are similar, but P. sillimani of Baffin Island, Canada (middle Katian), has a significantly larger first-formed shell that formed during an extended juvenile stage. This may have enabled the species to colonize newly exploitable habitats during an interval of rapid sea level rise in Laurentia during the Katian. This plasticity of developmental modes in the Dalmanellidae shows not only that using distantly related modern brachiopods as an analog for extinct Paleozoic lineages may be misleading, but also that development can vary within a single lineage and that timing of developmental stages should not be considered a reliable character for use in phylogenetic studies of brachiopods.

Buckling Analysis of Variable Stiffness Composite Cylindrical Shells Under Axial Compression Considering Imperfection Sensitivity

Thin-walled composite cylindrical shells are nowadays widely used as primary structures in the aerospace industry. The so-called variable stiffness (VS) composite cylindrical shells with flexible stiffness tailoring characteristics have been made possible by existing AFP techniques. Considering the inherent imperfection sensitivity property of axially compressed thin-walled cylindrical shells, the buckling behaviors of the axially compressed VS composite cylindrical shells with initial geometric imperfections and delamination imperfections are investigated respectively in this paper. The design buckling loads of the axially compressed VS composite cylindrical shells are first determined by the probing method, which is verified by comparing with the existing test data and numerical simulation results. Additionally, a parametric study is conducted to investigate the effects of delamination imperfections on the buckling loads. The constraint delamination sizes of the VS composite cylindrical shells based on the design buckling load in this paper are given. Furthermore, the effects of continuously variable fiber angles on the buckling loads are investigated considering the imperfection sensitivity. The specific VS composite cylindrical shells with both high- buckling loads and low-imperfection sensitivity are obtained. Results indicate that the effects of imperfection sensitivity need to be carefully considered in buckling design of the axially compressed VS composite cylindrical shells.

Digital twin method for the stress field of a deep-diving spherical shell based on a simulation database

In this paper, a Digital Twin (DT) method is proposed for quickly predicting the stress fields of deep-diving spherical shells based on a simulation database. The DT method can completely cover the stress field distribution of the entire pressure-resistant shell and provide stress predictions for different sizes of deep-diving protection shells. The DT model has a three-level structure. The Level-1 DT maps the Finite Element Model to the digital model, which is verified by experiments. The difference between the experimental and numerical results is less than 9.4%. Then, the Level-2 DT deduces the digital model and expands the simulation database samples. The uncalculated stress field results in the simulation database could be obtained by the local Lagrangian interpolation method. Furthermore, the Level-3 DT can rapidly predict the stress field distribution in deep-diving spherical shell digital models. By comparison with different optimization algorithms, the Particle Swarm Optimization algorithm demonstrates strong optimization capabilities and fast convergence, and the error compared with the simulation results is less than 1%. Finally, combined with actual sensor measurements and historical experience data, this method can be used to carry out real-time mapping and synchronous deduction of the service state of the dynamic stress digital twin.

Determination of Critical Moisture Content Facing Walnut Shell Breaking and Optimization of Combined Hot Air and Microwave Vacuum Drying Process

The conditioning of moisture content is an effective way to improve walnut-crushing performance. In this study, firstly, walnuts with different moisture contents were used to conduct the crushing experiments. The distributions of fragment sizes of shells and kernels with different moisture contents were analyzed by an image processing and sieving method, respectively. The results show that moisture content significantly affects the fragmentation degree of the shell and kernel, as shown by the differences in the fractal dimensions of shell fragments and the average fragment size of kernel fragments. The critical moisture contents of the shells and kernels, corresponding to the specific states of broken shells and whole kernels, were determined. Then, taking the critical moisture content as the target moisture content, the combination of hot air and microwave vacuum drying applied to dry walnuts was presented and the process parameters were optimized. Optimized process parameters include a hot air temperature of 63.23 °C, a moisture content of the transition point of 24.88%, microwave power of 588.24 W and a microwave vacuum thermostatic temperature of 49.01 °C. At this point, the unit time drying rate, unit mass drying energy consumption, mean square error of moisture content and kernel color parameters were 0.215%/min, 3.03 kW·h/kg, 2.93% and 6.42, respectively. It was confirmed that drying the walnuts to a critical moisture content using an optimized process could both maximally improve the crushing performance and significantly reduce the drying time. The findings provide important information for conditioning the crushing state of walnuts and improving crushing performance and have practical value for the improvement of drying systems.

Optimizing Mesh Sizes of Thin Shells Using Biomimicry for a Sustainable Solution

Nature always has the ability to offer various solutions in day-to-day life of humans in various fields of engineering and science. The term biomimicry refers to the process of adopting solutions from nature to solve complicated problems that refers to analysing the environment for sustainable solutions. This concept is used in various fields of engineering and science. This concept is emerging now in the field of construction also. Biomimics concept is used in analysing the behaviour of structural elements which forms a symbiosis between the environment and construction. In the field of construction, thin shell structures are lightweight structures that are preferred as roof elements for covering high spans and also gives an aesthetic appearance. In this study, three different shapes like spherical with different rise to span ratios, circular and elliptical are considered. The concept of reflecting the human skull shape into thin shell structures was considered, because the reflection from the environment helps in solving the complicated problems of both engineering and sciences. This study focused on the mesh convergence study for numerical analysis using Ansys 18.1 software. The parameters of the thin shells such as thickness, span and rise were taken from the geometrical characteristics of scanned human skull models in comparison with the standard skull models. From the results, mesh sizes were optimized for the three different shapes considered and also predicted the most efficient model. These results were obtained based on the equivalent stress in comparison with the theoretical stresses of the respective models. This study inspires the naturally available forms in the environment to incorporate it in the field of construction and technology for a sustainable solution.

Physicochemical Properties of Chitosan from Green Mussel Shells (Perna viridis): A Comparative Study.

Green mussel shells (Perna viridis) are generated in huge amounts and discarded as waste materials. Such waste may be used to produce biopolymer materials such as chitosan. The physicochemical properties of chitosan prepared from different sizes of green mussel shells (small size (CHS): ≤5.00 cm in length and big size (CHB): >5.01 cm in length) were characterized and compared with commercial chitosan (CH). Furthermore, the mechanical and physicochemical properties of the blended films were also investigated. The results of the physicochemical properties showed that CHS and CHB were quite different from CH. The degree of deacetylation of CHS, CHB, and CH was found to be 32.71%, 52.56%, and 70.42%, respectively (p < 0.05). The water- and fat-binding capacities of CH were higher than those of CHS and CHB. Structural differences between CHS, CHB, and CH were studied using Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD). Significant increases in thickness, water vapor permeability, and strength of the blended films were found when the extracted chitosan was added (p < 0.05). However, further study is needed to improve the chitosan extraction process, which can enhance the physicochemical properties of the obtained chitosan and be widely used in many industries.

Freshwater bivalves and their environmental conditions in a Jurassic lacustrine system (Cañadón Asfalto Formation) from Patagonia, Argentina

At the moment, two freshwater bivalve species were described for the continental Jurassic of Patagonia: Diplodon simplex Morton and Diplodon matildensis Morton from La Matilde Formation of the Santa Cruz province. The Cañadón Asfalto Formation located in Chubut province exhibits a high diverse invertebrate fossil fauna preserved mainly in lacustrine facies, which includes clam shrimps, bivalves, gastropods, ostracods and insects. However, few studies have been carried out on freshwater bivalve of this geological unit. In this work, a morphological description of bivalve assemblage and paleoenvironment analysis from the Cañadón Asfalto Formation was performed. Forty samples were collected from three stratigraphic levels at the Cañadón Asfalto locality. These levels are ash fall tuffs rich in glass particles accumulated in a lacustrine system with development of microbial activity. Morphological analyzes of outline and sizes were performed at each level. Our results showing the smallest-sized association of unionids recorded for the Jurassic time with size ranging from 7.6-11.7 mm long and 5.2-7.6 mm high. The environmental influence of pyroclastic falls could have played an important role in the development of the sizes of populations and shells.

Basic Formulation Semblance and Contemporary Approach of Mini Tablets

As a new approach to solid dosage forms, mini-tablets (MTs) are designed to subjugate some kind of therapeutic disincentives, like poor swallowing properties and polypharmacy therapy, as well as to provide therapeutic advantages like dose flexibility and release patterns. These pills are a viable method of delivering medication to patients. It has smaller tablets than typical, with a diameter of between 2 and 3 mm, compared to conventional tablets. Other advantages of tiny tablets include their uniform shape and size, which reduces unit-to-unit fluctuation in the medicine and allows for precise weighing of the substance. Since they have a very smooth surface area, it is possible to cover them with a drug-delaying coating in order to prolong their shelf life. It can also be used in the same way as other multiple-dose forms, such as capsules. MTs are a good substitute for pellets and granules. Lower potential drugs can be encapsulated as mini tablets in different sizes of gelatin capsule shells if the qualities are adequately regulated. This review article depicts various aspects of mini-tablets, such as their marketed product, types, formulation prospects, current trends of manufacturing, novelties in research work, and patent-related works that will be beneficial for those who are conducting research on the formulation and development of this mini tablet dosage form.

МАГНИТНЫЕ И СТРУКТУРНЫЕ СВОЙСТВА НАНОЧАСТИЦ ОКСИДОВ ЖЕЛЕЗА, ПОЛУЧЕННЫХ МЕТОДОМ ТЕРМИЧЕСКОГО РАЗЛОЖЕНИЯ СОЕДИНЕНИЙ-ПРЕКУРСОРОВ В РАСТВОРЕ

In this study, the method of thermal decomposition of iron(III) oleate at different ratios of oleic acid and octadecene-1 was used to obtain iron oxide nanoparticles (IONPs). Transmission electron microscopy (TEM) showed that they all had a spherical shape and a diameter of 8–9 nm, and FT-IR spectroscopy revealed the presence of oleate shells in them, which ensure the stability of the colloidal solutions of these nanoparticles in nonpolar solvents. For all synthesized IONPs, the sizes of the crystalline core formed by iron oxides were determined using X-ray diffraction analysis and magnetometry. The sizes of the oleate protective shells were established by comparison with the TEM data. These values were in agreement with those from the literature.

Temporal shell-size variations of bivalves in South China from the Late Permian to the early Middle Triassic

During the end-Permian mass extinction and subsequent Early-Middle Triassic recovery, a series of environmental changes occurred and were accompanied by morphological and ecological responses. This study presents a shell-size analysis study of Upper Permian through lower Middle Triassic bivalve fossils from South China to discover their ecological and environmental implications. With a dataset of over 4900 bivalve specimens from published monographs and our own collections, shell length and shell height are measured and analyzed with a substage-stage binned scale. The mean and median sizes of bivalve shells show a significant Lilliput effect in the immediate aftermath of the end-Permian mass extinction. However, both epifaunal and infaunal bivalves grew larger quickly during the late Griesbachian, indicating a quick rebound of bivalve shell size. The temporal variations in bivalves in South China were mainly controlled by biotic and abiotic factors, e.g., physiological adaptation, changing competition, predatory pressure, and climatic and oxygen changes.

Flash-light on the ring: hydrodynamic simulations of expanding supernova shells near supermassive black holes

ABSTRACT The way supermassive black holes (SMBHs) in Galactic Centres (GCs) accumulate their mass is not completely determined. At large scales, it is governed by galactic encounters, mass inflows connected to spirals arms and bars, or due to expanding shells from supernova (SN) explosions in the central parts of galaxies. The investigation of the latter process requires an extensive set of gas dynamical simulations to explore the multidimensional parameter space needed to frame the phenomenon. The aims of this paper are to extend our investigation of the importance of SNe for inducing accretion on to an SMBH and carry out a comparison between the fully hydrodynamic code flash and the much less computationally intensive code ring, which uses the thin shell approximation. We simulate 3D expanding shells in a gravitational potential similar to that of the GC with a variety of homogeneous and turbulent environments. In homogeneous media, we find convincing agreement between flash and ring in the shapes of shells and their equivalent radii throughout their whole evolution until they become subsonic. In highly inhomogeneous, turbulent media, there is also a good agreement of shapes and sizes of shells, and of the times of their first contact with the central 1-pc sphere, where we assume that they join the accretion flow. The comparison supports the proposition that an SN occurring at a galactocentric distance of 5 pc typically drives 1–3 M⊙ into the central 1 pc around the GC.

EXPERIMENTAL STUDY ON BED-TO-TUBE HEAT TRANSFER COEFFICIENTS IN BUBBLING FLUIDIZED BED

The overall bed-to-tube heat transfer coefficients of the blends of Lafia-obi coal and coconut shells have been investigated in a bubbling fluidized bed combustor. Experiments were performed at five different particle sizes of coal (5, 10, 15, 20 and 25 mm) and five different particle sizes of coconut shells (2, 6, 10,14 and 18 mm) for different blend proportions of 10%, 20%, 30%, 40% and 50%. Results obtained showed that the overall bed-to-tube heat transfer coefficient decreased with increasing coconut shell particle size in the blends. Combined effects of high radiation from large particle size of coal (25 mm) and high convection heat from small particle size of coconut shell (2 mm) at blend proportion of 10 and 50% produced the maximum bed-to-tube heat transfer coefficient. Due to the importance of heat exchange in the fluidized bed, it is observed that the contribution of biomass co-firing with coal is significant, hence, co-firing at optimal particle size and biomass blend ratio is imperative for achieving higher bed-to-tube heat transfer in the fluidized bed boiler.

Thermal conductivity of coconut shell particle epoxy resin composite

Coconut shell is one of the agricultural wastes that are widely available in Indonesia and other tropical countries. Unfortunately, the coconut shell waste has not been used optimally for new materials, especially for thermal insulation material. In this work, the composite from coconut shell particles using epoxy resin adhesives has been prepared. The particle sizes of coconut shells for composite samples were 60, 80, 100, and 120 mesh. The compositions of samples for each particle size (ratio between coconut shell and epoxy resin) were 70/30, 75/25, 80/20, and 85/15 (vol %). The thermal conductivity of each composite sample has been examined by using a single-plate method. The density of each sample has also been measured. The results showed that the thermal conductivity of composite sample for 60 mesh of particle size with 70/30 vol.% composition was 0.071 W/m K. As the composition of coconut shell was increased to 85 vol.%, the value of thermal conductivity decreased to 0.062 W/m K. It was found that the thermal conductivity of composite sample decreased as the composition of coconut shell was increased. For the composition of 70/30 vol.%, the thermal conductivity increased to 0.078 W/m K for 120 mesh of particle size. This behavior was also the same for other compositions, where the value of thermal conductivity of composite increased as the coconut shell particle size decreased. The density of the composite was found in the range of 0.799 – 0.938 g/cm3. As the particle size of the coconut shell was reduced, the density of the composite increased. This study revealed that both thermal conductivity and density of coconut shell epoxy composite are dependent on the particle size of the coconut shell. The thermal conductivity of all samples was less than 0.1 W/m K indicating that the coconut shell epoxy composite is quite potential for thermal insulation.

Radiation Induced Generation of Core–Shell Nanoparticles in Polyelectrolyte Films of Poly(acrylic acid)–Poly(ethylenimine) Complex with Copper and Silver Ions

Tuning the size and structure of bimetallic nanostructures is for the design of functional compounds with desirable properties. In this paper, the mechanisms that control radiation-induced assembly of bimetallic core–shell nanoparticles in polyelectrolyte matrices are discussed. The stages of Ag/Cu nanoparticle formation in the films of poly­(acrylic acid)–poly­(ethylenimine) complexes have been studied for the first time using X-ray diffraction analysis including synchrotron techniques combined with electron microscopy. The generation of silver nanostructures proceeds via their parallel nucleation and growth during the entire process of bimetallic nanoparticles formation. The sizes of shells are controlled by the competition between the growth of silver nanostructures and the formation of shells. Copper shells are generated in two stages: (1) ultrasmall nanostructures, which are slowly formed at the first stage, prevent the growth of silver nuclei; (2) as the shell improves, the growth rate of copper nanostructures increases dramatically. The results obtained demonstrate the possibility of single-stage controllable radiation-initiated synthesis of core–shell bimetallic nanoparticles directly in interpolyelectrolyte films.

Study of heavy metal content cadmium (Cd) in various sizes of blood shells (Anadargranosa) in coastal Bancaran Bangkalan, Madura

Ocean pollution occurs because of the concentration of population and industrialization in the coastal areas. The existence of heavy metals in the water can be accumulated in aquatic organisms, especially blood shells. The purpose of this study is to know the contents of cadmium (Cd) in blood shells, water, sediments and to determine the relation of blood shell’s size with the contents of cadmium (Cd) in the Bancaran Coastal, Bangka, Madura. The research method used was observations of that method. The main parameters are observed that the contents of cadmium (Cd) in seawater, sediment, and blood in the Bancaran Coastal shells. Supporting parameters that observed are water quality include temperature, pH, salinity, DO and brightness. Data analysis is used to find relations of the data Obtained (regression-correlation). The results showed that the contents of cadmium (Cd) of large shells blood are higher than the small and medium blood shells, and there were the relations between the size of the blood shells with the contents of cadmium (Cd). The water quality of Bancaran Coastal was the temperature 28°C-29°C, pH 7-8, the salinity of 30 ppt, the brightness of 30 cm, and DO 5 mg/L.

Size-based physical properties of hard-shell clam (Mercenaria mercenaria) shell relevant to the design of mechanical processing equipment

The knowledge of physical properties of food products is of fundamental importance for efficient design, dimensioning, manufacturing and operation of different mechanical equipment used in the processing of these products. Clams of different sizes are utilized during processing, thus, all the sizes must be given adequate consideration for efficient processing. This study was conducted to investigate the size-based physical properties of hard-shell clam (Mercenaria mercenaria) shell relevant to the design of mechanical processing equipment. The sizes of the clam shells were identified and categorized as small, medium and large; and its effect on the physical properties were studied. The parameters investigated were length, width, thickness, arithmetic and geometric diameters, surface area, sphericity, aspect ratio, moisture content, bulk and true densities, porosity, clam shell weight, coefficient of static friction and angle of repose. Increase in the length and width of clam shells increased the arithmetic and geometric diameters, and the surface area, but decreased the sphericity and aspect ratio. Moisture content, bulk and true densities, porosity and clam shell weight increased with increase clam shell size. Coefficient of static friction of clam shell was highest on rubber surface and lowest on glass surface, and was positively correlated with size; while angle of repose decreased with size. There was an excellent agreement between the prediction of the normal distribution and the actual distribution of the clam shell sizes. All the parameters were significantly different with respect to clam shell size at p < 0.05, which makes a strong case for the consideration of clam shell size during processing.

Cataloging Cowries: A Standardized Strategy to Record Six Key Species of Cowrie Shell from the West African Archaeological Record

Two species of the cowrie shell, Monetaria moneta (Linnaeus, 1758) and Monetaria annulus (Linnaeus, 1758), repeatedly occur in archaeological contexts across West Africa. Despite their archaeological and ethnographic importance, these shells remain poorly and inconsistently reported in the archaeological literature. The absence of standardized data on species composition, size, and condition of cowrie assemblages, and whether and how the shells were modified, make it difficult to examine their significance in a regional and chronological framework. To address this problem, we propose a set of standardized criteria and coding system for recording cowrie assemblages—in particular, species, size, condition, and state of modification. We aim to enable nonshell specialists within the wider archaeological community to securely identify intact or modified specimens of M. annulus and M. moneta, showing how these can be distinguished from four cowrie species native to West Africa—Luria lurida (Linnaeus, 1758), Zonaria zonaria (Gmelin, 1791), Zonaria sanguinolenta (Gmelin, 1791), and Trona stercoraria (Linnaeus, 1758). We demonstrate how accurate species identification and the assessment of proportions of different sizes of shells within suitably large assemblages can provide insight into their provenance. This information can enhance our appreciation of the exchange networks within which these shells moved. We also identify five different strategies documented in the archaeological record that were used to modify cowries, detailing how these can be differentiated and classified. The aim here is to suggest a recording strategy that will enable comparisons of the use and value of cowries in West Africa and elsewhere.

Brachiopod shell thickness links environment and evolution

AbstractWhile it is well established that the shapes and sizes of shells are strongly phylogenetically controlled, little is known about the phylogenetic constraints on shell thickness. Yet, shell thickness is likely to be sensitive to environmental fluctuations and has the potential to illuminate environmental perturbations through deep time. Here we systematically quantify the thickness of the anterior brachiopod shell which protects the filtration chamber and is thus considered functionally homologous across higher taxa of brachiopods. Our data come from 66 genera and 10 different orders and shows well‐defined upper and lower boundaries of anterior shell thickness. For Ordovician and Silurian brachiopods we find significant order‐level differences and a trend of increasing shell thickness with water depth. Modern (Cenozoic) brachiopods, by comparison, fall into the lower half of observed shell thicknesses. Among Ordovician–Silurian brachiopods, older stocks commonly have thicker shells, and thick‐shelled taxa contributed more prominently to the Great Ordovician Biodiversification but suffered more severely during the Late Ordovician Mass Extinction. Our data highlight a significant reduction in maximum and minimum shell thickness following the Late Ordovician mass extinction. This points towards stronger selection pressure for energy‐efficient shell secretion during times of crisis.

INTERNAL-POPULATION PROPERTIES OF HELIX ALBESCENS SHELLS IN THE NORTHWEST AZOV

A comparative analysis of the clonic features of the Helix albescens terrestrial molluscs collected in the natural and anthropogenic biotopes of the northwest Azov in 2017-2018 is carried out. Samples were taken from 10 habitats of molluscs living within the borders of Melitopol and the region. In total 1325 specimens of shells of H. albescens were collected. The results of studying the interpopulation and intrapopulation variability of Helix albescens in shell height (SH), large diameter (LD), small diameter (SD), mouth height (MH), mouth width (MW). The area of the mouth (S), the conditional volume (V), the relative height of the mouth, the shape of the mouth and a number of indices were calculated. Trees and bushes vegetation was dominated on the most points of collecting material. The connection between morphometric features of mollusc shells and biotopic peculiarities of their habitation is revealed. The average variability of the shell size in the most of the samples is found, the value of Cv is between 10 and 20%. The lowest coefficient values of variation among the 14 samples were recorded for such parameter as height of the mouth. Comparison of shells Helix albescens sizes from territories with different anthropogenic loading showed that in the city the shells are bigger than in the countryside. The maximum sizes of shells had molluscs, which were collected within the area of Melitopol at points located in biotopes with multistory buildings, private sector and gardens, the smallest - at points located outside the city. Correlation analysis showed a high level of correlation dependencies for all shell parameters. The main morphometric molluscs’ shell indices have changed in wider ranges, which indicates a high variability. But in general, the relevant indicators are at the average level indicated for these species within the range.